1. Field of the Invention
The present invention relates to an optical transmission module.
2. Description of the Related Art
JP2005-019746 A discloses a semiconductor laser device including a light-emitting element and a light-receiving element disposed in an accommodating portion, in which signal light from the light-emitting element is emitted through a transparent portion formed in a wall surface of the accommodating portion. The semiconductor laser device includes a scattered-light-shielding member for blocking scattered light, caused by the reflection of the signal light emitted through the transparent portion from the light-emitting element at the transparent portion, from being incident on the light-receiving element.
An optical transmission module that converts an electric signal to an optical signal and outputs the optical signal is provided with a light-receiving element for monitoring light emitted from a light-emitting element. The light-receiving element monitors a light output emitted from the light-emitting element, and the optical transmission module controls, based on the monitoring result, the intensity of the light emitted from the light-emitting element so as to be constant.
The light-receiving element is needed for each of light-emitting elements, so that an optical transmission module provided with a plurality of light-emitting elements is provided with as many light-receiving elements as the light-emitting elements.
Because of the demand for the miniaturization of the optical transmission module in recent years, when a plurality of light-emitting elements and a plurality of light-receiving elements are densely provided in one package, it is considered that leakage light or stray light from an adjacent light-emitting element, other than light emitted from one light-emitting element desired to be originally monitored, may also be incident on one light-receiving element.
When the leakage light or the like described above is incident on the light-receiving element, the light-receiving element cannot obtain a precise monitoring result. As a result, it may become difficult to control the intensity of the light emitted from the one light-emitting element so as to be constant.